The present invention relates to a flow meter, passage of flow measurement and production method thereof, and more particularly, to a flow meter, passage of flow measurement and production method thereof suitable for use in measurement of a flow of air taken into an internal combustion engine of an automotive engine.
As a laminarization lattice for an air flow meter, metal mesh, aluminum honeycomb or plastic is generally used. Here, as described in Japanese Patent No. 3245362, a laminarization lattice of a thin plastic molded product is molded as a part independent of a body component. Furthermore, in order to improve moldability of the laminarization lattice portion, a laminarization lattice shape (thickness of first lattice is approximately 0.3 mm, thickness of second lattice is approximately 1 mm) or the like is publicly known, which is composed of a reticular lattice having a first thickness and spacing and a second rib lattice having a thickness and spacing greater than the first thickness and spacing with the first reticular lattice and the second rib lattice being integrally molded.
According to a conventional technique, a body component and laminarization lattice component are molded as separate parts to enable a laminarization lattice which is a thin plastic molded product having a thickness of approximately 0.3 mm to be molded. This leads to a problem that a variation in assembly of the body and the laminarization lattice causes the air flow in the vicinity of a detector for detecting the air flow to change, provoking deterioration of measurement accuracy of an air flow meter. Furthermore, there is another problem that falling of the laminarization lattice due to assembly faults or the like provokes deterioration of measurement accuracy of the air flow meter. Moreover, since the body component and the laminarization lattice component are separate parts, the number of parts tends to increase and the cost also has a tendency to increase due to an addition of assembly work. Furthermore, since the second rib lattice is made thicker to improve moldability of the lattice, there is also a problem that pressure loss of the lattice increases. Furthermore, making the rib lattice thicker to improve moldability causes the rib lattice to generate air disturbance, provoking deterioration of measurement accuracy.
Therefore, it is an issue to be addressed how to reduce degradation or deterioration of measurement accuracy of an air flow meter caused by low cost, assembly variation or assembly faults and suppress an increase in pressure loss of a lattice or deterioration of measurement accuracy of the air flow meter caused by making a rib lattice thicker to improve moldability.
It is an object of the present invention to realize a low cost, high accuracy flow meter, passage of flow measurement and production method thereof by integrally molding a passage and a lattice and reducing the number of parts.